When installing and maintaining underground fluid pipelines, the joints between pipe segments are encased in a collar which is filled with a sealant to prevent leakage of fluid through the joint. In large pipelines, the joints are of the bell-and-spigot type. The collar often comprises a flexible sheath which is wrapped around the pipe in the area of the joint and is secured thereto by metal or plastic strapping. The sheath includes a fitting through which a suitable sealant may be introduced into the interior of the sheath around the joint. The sealant is confined by the sheath so that it may cure and provide a leakproof seal around the joint. In some cases the sealant is sufficiently fluid to be poured into the sheath manually; however, it is preferable to employ a more viscous sealant material which must be pumped into the interior of the sheath to provide a localized mass of sealing material which readily cures without danger of penetration into the interior of the piping. In such instances, the sheath may be provided with a vent fitting which permits the injected sealant to exhaust any residual air from the interior of the sheath.
When the sealed joint is formed in a pipeline system located close to the ground surface, i.e., within arm's length of the ground surface, workmen have no difficulty in manually wrapping the sheath about the joint. When the pipeline system is located more than an arm's length below the ground surface, an excavation surrounding the joint must be prepared to allow a workman access to the joint for manually installing the collar to seal the joint. The excavation must be sufficiently large to permit the workman to physically enter the excavation and manipulate the sheath around the joint.
Preparing an enlarged excavation according to this procedure substantially increases the time and expense needed to seal the joint. Further, workmen often shortcut the need for a full size excavation by suspending a workman head-downwards into the excavation for the purpose of applying the sheath. Such a practice is contrary to safe work rules and may lead to improper installation of the collar around the joint. Additionally, even when a workman properly prepares and enters a full excavation, the workman risks intoxication or suffocation from toxic liquids leaking from the joint, or great bodily injury from a collapsing excavation.